Gasoline engine ignition system



March 17', 1942. c. w. HANSELL GASOLINE ENGINE IGNITION SYSTEM Filed Sept. 20, 1940 INVENTOH CLARENCE W.HAN$ELL BY /uru- ATTORNEY Patented Mar. 17, 1942 GASOLINE ENGINE IGNITION SYSTEM' Clarence W. Hanaeli, Port Jefferson, N. I, assignor to Radio Corporation of America, a corporation of Delaware 7 Application September 20, 1940, Serial No. 357,537

10 Claims.

, This invention relates to a new and useful ignition system for gas engines generally.

An object of this invention is to improve the performance of gas engine ignition systems, and particularly such engines as are applied to automobiles, which require means to suppress radio interference.

which gives rise to a need for improved performance of the ignition system and for shielding of the ignition system to suppress interference in the automobile receiver.

A feature of this invention is the novel arrangement within a metallic spark plug shielding member of a condenser, a resistance and an inof Fig. 1, except that an auxiliary spark gap is placed between the inductance and the high po- I'he present trend at this time is I to equip automobiles with a radio receiving set ductance, and in another modification, an auxiliary spark gap located in series between the high potential electrode of the spark plug and an inductance.

In the prior art, ignition systems have been provided with separate metallic shields and with resistances in series with the spark plugs, for reducing radio interference. Also. auxiliary spark gaps in series with spark plug gaps have been used to improve the ignition system. However, no attempt, insofar as I am aware, has been made to emphasize radio frequency oscillations through each individual spark plug while, at the same time, means is provided to effectively suppress radio interference.

I have found that a fouled spark plug, in the absence of an auxiliary gap, as provided for in this invention, would simply short-circuit the ignition circuit and thus give rise to frequent trouble. However, when the auxiliary gap is added, a spark may be produced across the auxiliary gap even when the spark plug in series with it is foul. The spark in the extra gap then gives rise to radio frequency oscillations through the fouled spark plug. These oscillations greatly increase the peak instantaneous flow of electrical charge, or t'otal current, through the plug, acting like any radio spark transmitter circuit. The radio frequency oscillations due to the high peak currents produced and due to high frequency skin effect tend to burn away small accumulations of carbon and to cause sparks across small gaps in it, which sparks are often suflicient to ignite the charge in the engine cylinder even when the plug was badly fouled. By my invention, I propose to further improve the operation of ignition systems by adding a shielded metallic member for the spark plug, an inductance in series with the spark plug, and a capacity to the high potential leads to improve the ignition system even without the addition of auxiliary spark gaps.

This invention will be more completely understood by referring to the accompanying drawing, in which:

Fig. 1 shows a circuit diagram of the improved ignition system of this invention;

Fig. 2 shows a circuit diagram similar to that tential side of the spark plug electrode; and

Fig. 3 showsa circuit diagram in which an auxiliary,, spark gap is placed in series with a resistance and an inductance.

Referring now in detail to the drawing, I is a distributor head of a six-cylinder gasoline engine and for the sake of simplicity, only one of the cylinders is shown having its high tension lead connected from the distributor to the spark plug, although by my invention, every cylinder will have its high tension lead from the distributor to the spark plug arranged with the improved inductance and resistance device shown in Fig. 1. The high tension lead 2 connects to a resistance 3 and an inductance coil 4. A lead 5 connects coil 4 to the high potential electrode of a spark plug 6. A condenser I ls connected from the junction point of the resistance and the inductance coil to the low potential or ground side of the spark plug electrode which is indicated at 8. The resistance, inductance coil and condenser are enclosed within a metallic shield 9. Lead 2 is inlsailated from casing 9 by an insulating bush- The arrangement in Fig. 2 is similar to that circuit arrangement shown in Fig. 1, except that an auxiliary spark gap II is connected in series between inductance coil! and spark plug 6.

Fig.- 3 shows another modification of the circult arrangement wherein the auxiliary spark gap Ii is placed in series between the junction point of the condenser l and resistance 3, thus placing the auxiliary gap in series between the resistance and the spark gap 6, except that inductance 4 is connected directly to lead 5 which connects to spark plug 6, In order to get efilcient results from this invention, it is desirable that resistance 3, inductance 4, condenser I and spark stantaneous current through the gap which is far greater than could be obtained directly from the distributor through the series resistance. Furthermore, the condenser discharge is oscillatory in nature whereas in the usual ignition system where resistances in series with the spark plugs are employed as radio noise suppressors, the tendency is for the resistances to strongly suppress or reduce oscillation. It is because of the lower peak current and suppression of oscil-.

depended upon to supply inductance for oscillation.

In the arrangements of Figs. 2 and 3, the auxiliary gaps provide for higher peak currents and an oscillatory discharge even when plugs are so fouled that electrical leakage would otherwise prevent the building up of high potentials across the condenser. The leakage frequently has no substantial eflect upon flring whe'n the auxiliary gap provides for obtaining themuch higher instantaneous currents. Here, again, the inductance coils 4 can be omitted, depending upon lead inductance to provide for oscillation.-

In the arrangements of. all three figures, the resistances 3 act as suppressors or filter elements to reduce the leakage of high frequency oscil-- latory energy out over the leads to the distributor. In addition, the leads and distributor may be more or less shielded to obtain still better noise suppression or to permit lower resistance values to be used.

Still better results may beobtained by plating or coating spark plug surfaces with low resistfailure to func ion. Carbon in these systems usually forms in' a feathery, crystalline or spongy structure which, when it first bridges the ignition gaps to short-circuit them, has low current trode of said spark plug, a lumped condenser connected from the junction point of said inductance and resistance to the other electrode of s aidspark plug, and a, metallic shield enclosing said resistance; inductance, condenser and spark plug.

carrying capacity. By means of the invention,

heavier electricalcurrents are employed which can burn away light carbon formations and prolong the operation of the system, or even prevent failure altogether in many cases.

What is claimed is:

1. An ignition system for a gas engine comprising a source of high potential, a spark plug, a lumpedresistance lo'cated between said source and the high potential electrode of said spark plug, a lumped condenser connecting that terminal of the resistance nearest the spark plug to the other electrode of said spark plug, and a shield surrounding said resistance, condenser and spark plug.

2. An ignition system for a gas engine comprising an intermittent source of high potential,

a spark, plug, a lumped resistance located between said source and the high potential electrode of said spark plug, a lumped condenser connected from that terminal of the resistance nearest the plug to the other electrode of said spark plug, and a metallic shield enclosing said resistance, condenser and spark plug.

3. An ignition system for a gas engine comprising a source of high potential, a spark plug. and a series circuit made up of a resistance and an inductance, in the order named, connected between said source and the high potential elec- 4. A gas engine ignition system comprising a source of high potential, and a spark plug, a

series circuit composed of a resistance, a spark gap and an inductance located between said source and the high potential electrode of said spark plug, and a condenser connected from a point between said inductance and resistance to the other electrode of said spark plug.

5. A gas engine ignition'system comprising a series circuit made up of. .a resistance, a spark gap, and an inductance in the order named and connected to thehigh potential electrode of a spark plug, and a condenser connected from a point between said inductance and resistance to the other electrode of said spark plug;

6. A gas engine ignition system comprising a resistance and a spark gap in series relationand in the order named connected between the high potential electrode of a spark plug and a source of high potential, a condenser connected between that terminal of the resistance nearest the sparkplug and the other electrode of. said spark plug, and a metallic shield enclosing said resistance, spark gap, spark plug and condenser.

-7. A gas engine ignition system comprisinga resistance and a spark gap, and an inductance in series with and locatednear the high potential electrode of a spark plug, a condenser connected from the junction point of said induct-- ance and resistance to the other electrode of said spark plug, and a metallic shield enclosing said inductance, resistance, spark gap, spark plug by passing through said insulating bushing, and

a condenser connected between the other electrode of said spark plug and said resistance.

9. A gas engine ignition system comprising a metallic casing for enclosing a spark gap, an insulating bushing passing through said casing, a resistance, an inductance and a condenser located within said casing, said inductance and said resistance connected to the high potential electrode of said' spark plug and connected through a distributor for said gas engine by passing through said insulating bushing, and a condenser connected between the other electrode of said spark plug and the junction point of said resistance and said inductance.

10. A gas engine ignition system comprising a metallic casing for enclosing the high potential end of a spark plug, an aperture in said casing, a series circuit including a resistance and an inductance located within said casing 'and 

